Therefore, from the perspective of the acetone liquid, it is positive because it is absorbing heat from its surroundings. This absorption of heat is what drives the evaporation process.
From the perspective of the nail polish remover as a whole, it is negative because it is losing heat into the environment. This loss of heat is what makes the nail polish remover feel cold as it evaporates.
So it really depends on what your point of reference is, however, in chemical terms the process is positive.